Not Applicable.
This invention relates to cellular call delivery services provided by cellular/PCS operators. Call delivery service permits a cellular subscriber to receive phone calls either in a home network (e.g., London) or while away from the home network (e.g., in Chicago).
Global Systems for Mobile Communications (GSM) is a widely popular Time Division Multiple Access (TDMA)-based standard used in Europe, China, selected parts of the United States, and other parts of the world. TDMA is a digital wireless technology.
A GSM subscriber who roams to Code Division Multiple Access (CDMA) wireless networks or other Time Division Multiple Access (TDMA) networks may be denied wireless services even if the subscriber""s mobile device is capable of multi-mode (TDMA, CDMA, or analog, and GSM) operation, and the subscriber has the ability to pay for wireless calls with his/her valid credit card. The basis for the denial of service is simply because there does not exist a GSM Memorandum of Understandings (MoU) between the home GSM network and visited CDMA network for billing settlement. Similarly, a CDMA or TDMA subscriber who roams to GSM wireless networks may be denied wireless services even if that subscriber""s mobile device is also capable of multi-mode operation, where again the basis for the denial of service is simply because there does not exist a GSM Memorandum of Understandings (MoU) between the home CDMA or TDMA network and visited GSM network for billing settlement.
The existing infrastructure uses at least two disparate networks to implement call delivery service to roaming wireless users. A first network is a control and signaling network that links authorization centers, billing centers, location tracking, and so forth. Examples of control networks include GSM MAP networks and ANSI-41 networks. A second network is a voice network that links calls from one location to another. The Public Switched Telephony Network (PSTN) is one example of a widespread voice network used to transmit calls from one location to another. In the present practice, the control and signaling network is used to track the location of a mobile device, and when a call must be delivered to the mobile device, the PSTN network is used to route the call itself.
1. Field of the Invention
This invention relates to cellular telephony and the use of Internet Protocols and IP networks to replace traditional telephony setup infrastructure for roaming cellular users. This invention also relates to the field of providing mobile wireless telephone service for users roaming outside their own predefined service area. This invention also relates to the field of interoperability of CDMA and GSM/TDMA cellular networks.
2. Description of Related Art
A GSM MoU is an agreement between a consortium of GSM wireless service providers to coordinate billing settlement via a GSM MAP network. For example, a subscriber of a first GSM service provider may roam to a service area controlled by a second GSM service provider. An established MoU allows the first GSM service provider to still serve the subscriber while that subscriber is in the service area corresponding to the second GSM service provider. In practice, the second GSM service provider gets paid a portion of the service/roaming charge the first GSM service provider charges the subscriber, which is one reason wireless xe2x80x9croaming chargesxe2x80x9d are so expensive.
GSM MoU can also be used to coordinate billing settlement between GSM and CDMA (or TDMA) service providers. For example, a subscriber of a GSM service provider may roam to a service area controlled by a CDMA service provider. Assuming the user has a mobile device capable of multi-mode (in this example, GSM and CDMA) operation, an established MoU allows the GSM service provider to still serve the subscriber while that subscriber is in the service area corresponding to the CDMA service provider. In practice, the CDMA service provider gets paid a portion of the service/roaming charge the GSM service provider charges the subscriber.
The Local Number Portability (LNP) feature could be used, to some extent, to bypass the lack of a GSM MoU. LNP allows a telephone subscriber to xe2x80x9cportxe2x80x9d his/her phone number when that subscriber relocates to a different region of the country, even when the local area code may be different (e.g., a subscriber may reallocate from Chicago to New York, but still keep the original phone number used in Chicago that has an area code of 312).
However, LNP updates are not dynamic by design and thus can have serious limitations. A subscriber who wants LNP typically will request that service by filling out a form. The phone company""s administrative staff will manually process the form and make necessary updates of various databases to effect the requested LNP. Note that LNP is designed to support occasional change of location/re-location, and is typically done manually; thus, there is a scalability issue in practice.
Public Switched Telephony Network (PSTN) refers to the public phone networks as we know them. PSTN is composed of switches and T1/E1 trunks, central office, etc. PSTN uses circuit-switched technology, in which necessary resources are allocated (dedicated) for the duration of a phone call. An IP network (e.g., the Internet), in contrast, is composed of nodes of computers, serves, routers, and communications links, etc. It employs packet-switching technology that decomposes data (e.g., voice, web pages, an e-mail message) into IP packets. Each packet is then transmitted over an IP network to a destination identified by an IP address and reassembled at the destination. An IP transmission is completed without pre-allocating resources from point to point.
H.323 is a (long) list of standards that supports xe2x80x9cvoice over Internetxe2x80x9d (or voice over IP) and multimedia over Internet. As of the date of this disclosure, the URL databeam.com has further information on the H.323 standards. H.323-based packet calls can bypass some portion of telephony infrastructure, but H.323 does not provide for mobility and radio resource usage is inefficient if IP packets are carried over the radio link.
Mobile IP is described by Internet Engineering Task Force (IETF) Request for Comments (RFC) number 2002. As of the date of this disclosure, RFC 2002 may be obtained from URL nic.mil/ftp/rfc/rfc2002.txt. Unlike H.323, Mobile IP does support packet mobility, but smooth handoffsxe2x80x94as smooth as circuit cellular voicexe2x80x94are not supported.
One known commercial use of Mobile IP is deployed by Nextel, a wireless service provider. Using a cellular mobile phone by Motorola Corporation of Schaumburg, Ill., under the tradename iDEN 1000, Nextel allows subscribers to access digital data from the Internet via Mobile IP.
The Diffie-Hellman algorithm is a math method allowing two parties to establish a temporary secret for secure transmission of information. Reference: Diffie, W. and Hellman, M., xe2x80x9cNew directions in cryptography,xe2x80x9d IEEE Transactions on Information Theory, Vol. IT-22, November 1976, pp. 644-1654.
This invention addresses the above issues of denial of service by combining and integrating the proper pieces of circuit and packet, and that of wireless and wireline. This invention provides a way to bypass SS7 networks, GSM MoU, IS-41, and PSTN so that GSM users roaming into analog, TDMA, or CDMA networks, and CDMA users roaming into GSM, TDMA, or analog networks, and TDMA users roaming into GSM, CDMA, or analog networks, each having the ability to pay cellular calls with his/her credit card, can be provided with basic call delivery cellular services.
These and other aspects and attributes of the present invention will be discussed with reference to the following drawings and accompanying specification.